A composition for producing a glass fiber, including the following components with the corresponding percentage amounts by weight: SiO2: 58-62%; Al2O3: 14-18%; CaO+MgO: 20-24.5%; CaO: greater than 14%; Li2O: 0.01-0.5%; Na2O+K2O: less than 2%; TiO2: less than 3.5%; Fe2O3: less than 1%; and F2: less than 1%. The weight percentage ratio of CaO/MgO is greater than 2 and less than or equal to 2.6; and the weight percentage ratio SiO2/CaO is between 3.3 and 4.3. The invention also provides a glass fiber produced using the composition and a composite material including the glass fiber.